public class Euler436 {
    public static String solve() {
        double e = Math.E;
        double ans = (1.0 + 14.0 * e - 5.0 * e * e) / 4.0;
        return String.format(java.util.Locale.US, "%.10f", ans);
    }

    public static void main(String[] args) {
        System.out.println(solve());
    }
}